PHOENIX -- Rockies first baseman Ian Desmond left Saturday night's 2-1 victory over the D-backs after six defensive innings with soreness in his right knee, manager Bud Black said.
Desmond was 1-for-2 with a second-inning single off D-backs starter Zack Greinke. Rookie Ryan McMahon replaced Desmond to lead off the seventh against D-backs righty reliever Fernando Salas. 
Going with the left-handed McMahon against Salas was a defensible matchup, with McMahon coming off a big spring and not having started yet. But the decision wasn't fully explained until the injury was announced. The club called Desmond's status day to day.
"He's felt it the last couple of days … when he's in his stance, putting weight on his back knee," Black said. "It got a little bothersome and Ian came to me and said, 'Buddy, it's probably the right thing to do and let's get Mac in there.' He wasn't at full strength as the game went on."
Desmond went 4-for-10 -- including a two-run homer Friday night -- as the Rockies dropped two of three in the season-opening series.